As part of the upcoming September 2018 update, Office 365 for Mac users on macOS 10.12 or later will receive an update from the Office 2016 for Mac client to Office 2019 for Mac in order to maintain access to new feature releases and updates. Office 365 customers remaining on older macOS versions with Office 2016 for Mac will receive mainstream support, but not new Office 365 features.

tl;dr

macOS 10.10-10.11 deploy 16.16.x

macOS 10.12+ deploy 16.17.x

After which, if wanting to volume license you’ll need to apply the correct Volume License Serialiser.

AutoPkg

If you’re using AutoPkg, (& if not, why not?), please also read this post from Anthony Reimer.

Patch

If you’re using Jamf’s patch, double check your definitions as there are a number of discussions on these changes on Jamf Nation: